Yeah, if it was possible to make a 7lb Gauss rifle with the power of a .357 in your garage, I'd be building one right this minute.

The real problem with coilguns is the energy efficiency. Based on what I've read, the upper limit for efficiency for a basic coilgun with a small number of stages is somewhere in the 3-5% range. Contrast that with 30-40% for today's firearms.

To raise the efficiency to something approaching a practical weapon, you need to start adding lots of coil stages and very fast switching mechanisms with precise timing, in addition to some really big capacitors, high quality magnets, and a power source to match. All of which drastically raise the price of the weapon. I think for the hobbyist market, the best you're going to be able to do is a 20lb rig that's about as powerful as a .22LR.

Yeah, if it was possible to make a 7lb Gauss rifle with the power of a .357 in your garage, I'd be building one right this minute.

The real problem with coilguns is the energy efficiency. Based on what I've read, the upper limit for efficiency for a basic coilgun with a small number of stages is somewhere in the 3-5% range. Contrast that with 30-40% for today's firearms.

To raise the efficiency to something approaching a practical weapon, you need to start adding lots of coil stages and very fast switching mechanisms with precise timing, in addition to some really big capacitors, high quality magnets, and a power source to match. All of which drastically raise the price of the weapon. I think for the hobbyist market, the best you're going to be able to do is a 20lb rig that's about as powerful as a .22LR.

honestly, the biggest drawback to the coil theory is the coils. the pulses start approaching energy levels where inductance rears its ugly head and you start crushing the barrel as the coil deforms. there are ways around this but it's still pretty ugly. carbon fiber's out as it attenuates magnetic fields something fierce(nice to put over the body of the gun tho). even non-magnetic metals will form reactive eddy currents that degrade performance.

the upper limit on coil/gauss guns is really low, sadly.

now, i toyed with plasma conversion once... that was pretty exciting. dump enough energy into 1 gram copper pellet with magnetic induction and it turns into very energetic plasma... my wife never lets me forget taking the roof off the shed with the mark 1.

if you could get the plasma to stay roughly coherent at range, it'd be pretty ugly results on impact, with almost no recoil for the shooter.

granted the gun would be huge because the powerlevels are in the megajoule range...

buttery_shame_cave:now, i toyed with plasma conversion once... that was pretty exciting. dump enough energy into 1 gram copper pellet with magnetic induction and it turns into very energetic plasma... my wife never lets me forget taking the roof off the shed with the mark 1.

if you could get the plasma to stay roughly coherent at range, it'd be pretty ugly results on impact, with almost no recoil for the shooter.

granted the gun would be huge because the powerlevels are in the megajoule range...

Cthulhu_is_my_homeboy:buttery_shame_cave: now, i toyed with plasma conversion once... that was pretty exciting. dump enough energy into 1 gram copper pellet with magnetic induction and it turns into very energetic plasma... my wife never lets me forget taking the roof off the shed with the mark 1.

if you could get the plasma to stay roughly coherent at range, it'd be pretty ugly results on impact, with almost no recoil for the shooter.

granted the gun would be huge because the powerlevels are in the megajoule range...

Cool. Since it was a copper pellet, did it make big green fireballs?

more like green bolt of lightning and lots of sound and splinters raining down from the approximate 5-6' hole it made in the plywood of the roof. near as i can tell i had some focusing going on from the ring coil that was doing the energy transfer, and inductance in the baseplate squirted it up into the roof rather than letting it vaporize the workbench.

i'm just glad i was standing at the other end of the shop when it fired... from 10 feet away the heat was like standing in front of a blast furnace for a brief instant. had a bit of sunburn on the small patches of skin not covered by my welding gear.

if i could figure out how to efficiently direct and focus it, and keep it focused over distance, it'd be hellacious stuff at range with freakishly high velocity. not light-speed but damn higher than a bullet.

but that's a sidelined project. the current planning is for a LED array laser built out of scrapped optical drives. the fun part is it scales nicely if i can keep the optics properly cooled.

Kahabut:Now, the military has come up with something even better. They used a linear accelerator (it's a ring) to bring .50cal ball bearings up to a very high velocity inside the ring. Then, when you hit the trigger, it releases 3-5 ball bearings down the barrel. The impact energy is 10x higher than a Barret 50 cal rifle at the same range. They are currently using these as Humvee mounted weapons in Iraq... or at least they were using a few as a test, I'm not certain how that testing went.

grinnel:Kahabut: Now, the military has come up with something even better. They used a linear accelerator (it's a ring) to bring .50cal ball bearings up to a very high velocity inside the ring. Then, when you hit the trigger, it releases 3-5 ball bearings down the barrel. The impact energy is 10x higher than a Barret 50 cal rifle at the same range. They are currently using these as Humvee mounted weapons in Iraq... or at least they were using a few as a test, I'm not certain how that testing went.

Also, cool as it is, it's only about as powerful as a BB gun. Actually with the right pellets, my Crosman Phantom air rifle has about twice as much muzzle energy. Sadly it's not semi-auto, though.

From the video, it's actually pretty small, about pistol sized. I don't know the engineering enough to judge whether or not you could expand that design from four stages to N, but I'm thinking a rifle length set of coils with the batteries and capacitors in a backpack might put it past the air rifle stage.

Also, cool as it is, it's only about as powerful as a BB gun. Actually with the right pellets, my Crosman Phantom air rifle has about twice as much muzzle energy. Sadly it's not semi-auto, though.

From the video, it's actually pretty small, about pistol sized. I don't know the engineering enough to judge whether or not you could expand that design from four stages to N, but I'm thinking a rifle length set of coils with the batteries and capacitors in a backpack might put it past the air rifle stage.

And then it would still be inferior, in every possible way, to this:

[www.allmilitaria.com image 631x386]

I dunno, it was pretty damn quiet

If you used a heavy, subsonic projectile there might be a niche for Gauss guns as a silent weapon. The velocity wouldn't have to be all that high if you were tossing a 2 oz steel rod at somebody's skull. Maybe 400, 500 feet per second. That'd give you about the same energy as a .45 Colt but with twice the momentum. It would do Bad Things to a human, and being steel, would be more effective against light armor and obstructions.

That is, as long as charging the caps didn't make an incredibly loud high pitched noise. And you were willing to carry around a huge battery pack. To get 600J with 3% efficiency you'd be burning through about 500 mA-hr a shot from a 12V battery.

Also, cool as it is, it's only about as powerful as a BB gun. Actually with the right pellets, my Crosman Phantom air rifle has about twice as much muzzle energy. Sadly it's not semi-auto, though.

From the video, it's actually pretty small, about pistol sized. I don't know the engineering enough to judge whether or not you could expand that design from four stages to N, but I'm thinking a rifle length set of coils with the batteries and capacitors in a backpack might put it past the air rifle stage.

And then it would still be inferior, in every possible way, to this:

[www.allmilitaria.com image 631x386]

I dunno, it was pretty damn quiet

If you used a heavy, subsonic projectile there might be a niche for Gauss guns as a silent weapon. The velocity wouldn't have to be all that high if you were tossing a 2 oz steel rod at somebody's skull. Maybe 400, 500 feet per second. That'd give you about the same energy as a .45 Colt but with twice the momentum. It would do Bad Things to a human, and being steel, would be more effective against light armor and obstructions.

That is, as long as charging the caps didn't make an incredibly loud high pitched noise. And you were willing to carry around a huge battery pack. To get 600J with 3% efficiency you'd be burning through about 500 mA-hr a shot from a 12V battery.

supercapacitors charge bloody fast and REALLY quiet. the downside is that their oomph is delivered at low voltage. if you could get them up to a few hundred volts you could more easily deliver the amps neccesary to deliver a shot with a fast quiet charge that's got the juice to do some damage. any supercapacitor array that charges to hundreds of volts is going to be impractically large.

/supercaps... low voltage, tons of storage.

trouble is, you need a flyback generator to charge at hundreds of volts. which makes lots of noise.

sure you could make a one-shot gun that's totally silent and disposable, but given that there's chemical based versions of those out there that are far lighter and cheaper...

EM-powered weapons as personal weapons are, right now and for teh forseeable future, the stuff of fantasy and wishful dreaming. we just can't get the energy densities AND discharge times with materials that can hold up to the load to make man-portable, much less practical EM guns.

MrTuffPaws:That is a coil gun. A gauss gun is different. A coil gun uses coils to pull a projectile via magnetism. A gauss gun puts current through the projectile that causes a magnetic field between the two rails that pull the projectile. Guass guns don't have coils.

According to Wikipedia, the term "Gauss Gun" is used to describe a coil gun. Link

Biv:Cosmoboy: nekulor: Where I'm from, we have traditions and decorum. Those traditions dictate we have the decency to use shells in our railguns, thank you very much.

Why would you ever put a shell in your railgun? That shiat can explode. Just use slugs,man,slugs.

Depleted Uranium slugs with white phosphorus tips.

That's how I roll with my railgun

Uhm, usually in scifi, railguns use a form of flechette round. Basically like driving 20-50 nails through most material at Mach 2-10. DU rounds might have less of an effect at those speeds.

Ed Finnerty:I would have never survived Quarry Junction without my gauss rifle.

I used the unique gauss rifle weapon there, taking deathclaw heads off from across the quarry. For the alpha male and the queen, I actually used a modified sniper rifle with AP ammo. Boone had an anti-material rifle but he didn't get to fire it unless one got too close, which happened a couple of times; only took one of those to bring them down too.

Bendal:Ed Finnerty: I would have never survived Quarry Junction without my gauss rifle.

I used the unique gauss rifle weapon there, taking deathclaw heads off from across the quarry. For the alpha male and the queen, I actually used a modified sniper rifle with AP ammo. Boone had an anti-material rifle but he didn't get to fire it unless one got too close, which happened a couple of times; only took one of those to bring them down too.

Once I got the Sniper Rifle (and eventually the unique one... Christine's?) that was pretty much it. Upgrade it and keep the various ammo types on hand, and combined with a focus on the Guns skill and related perks, it's basically the only gun you need for any situation. Blowing the heads off deathclaws from a mile away.

I did climb up to the mountains ringing quarry junction once and threw in nukes with the Fat Man, just for fun.